1. Field of the Invention
The present invention relates to a hearing aid, and more particularly to a hearing aid allowing necessary sound only to be selectively heard.
2. Description of the Related Art
General microphones of hearing aids, of whatever type such as a type being inserted into an external auditory meatus, a type being used hung on an ear, or a type being separated from a hearing aid body, are used attached around ears or to bosoms.
Those need hearing aids have relatively narrow dynamic ranges. Thus, in the above described fixed microphone of the conventional hearing aid, microphone gain is set high to obtain an appropriate input level, and automatic gain control (AGC) is sufficiently performed, thereby allowing sudden loud sound such as impulsive sound to be appropriately reduced and transmitted.
FIG. 2 is a block diagram showing a configuration example of a conventional hearing aid. A microphone 33 picks up an audio signal, and an automatic gain controller 34 detects variation in amplitude of the audio signal and automatically controls gain of an amplifier so as to keep the amplitude of the output signal constant, and the signal is amplified by a microphone amplifier 35, frequency corrected by an equalizer 36, and with a power amplifier 37 driven, output from a speaker 38.
However, the conventional hearing aid reacts to unintentional and unnecessary sound such as a rubbing sound of newspaper when a user reads a newspaper, and operates, and the sound is amplified to thereby make the user uncomfortable.
Also, the automatic gain control is performed in accordance with voice of a nearby person or voice of a loud person to sometimes cause difficulty in catching voices of other persons, so that the conventional hearing aid is not suitable for a situation like a meeting that requires a conversation with a plurality of persons.
The present invention is achieved in view of the above described problems of the conventional art, and has the object to provide a hearing aid that allows desired sound to be selectively heard and allows unnecessary sound not to be heard, and that can be used with no bars even in a situation like a meeting that requires a conversation with a plurality of persons.
The above described problem is solved by a hearing aid according to the present invention, including: a hearing aid body having a hearing aid function and an external microphone signal receiving function; and a separate external microphone, wherein connection and disconnection of communication between the above described hearing aid body and the external microphone are automatically switched, and the above described hearing aid body functions as a normal hearing aid when the communication between the above described hearing aid body and the external microphone is disconnected.
Preferably, the communication between the above described hearing aid body and the external microphone is wireless communication, the communication between the above described hearing aid body and the external microphone is disconnected when the above described hearing aid body and the external microphone are joined, and the communication therebetween are connected when the above described external microphone is separated from the above described hearing aid body.